Adrian Benepe donned swim trunks for the opening of McCarren Park pool (after the ribbon cutting, he jumped in and swam a lap). High Line co-founder Robert Hammond remembers him in bike shorts during the elevated park’s inaugural weekend. But on the steamy evening when the New York Restoration Project held its annual fund-raising dinner at Gracie Mansion, Mr. Benepe was dressed conventionally in a suit, albeit with a backpack slung somewhat incongruously over one shoulder.

The backpack, like the granola bars that he keeps in his office, suggested a recent or upcoming tromp through some greensward more rugged than Carl Schurz, making it an agreeable accessory for an event aimed at rehabilitating neglected parks. But the former parks commissioner—for that was how people introduced him, despite the fact that he has been working at the Trust for Public Land for the past year—checked the bag at the entrance.

Leaving behind the “best job in the world” at the New York City parks department, where he spent the better part of 40 years and the near entirety of his professional career, has been more difficult. Mr. Benepe no longer presides over the 29,000-acre emerald empire whose transformation from overgrown, shabby and often-frightening urban wilderness into one of the city’s major tourist attractions has paralleled not only New York’s shift from a down-and-out city to an almost terrifyingly prosperous one, but also his own rise through the department’s ranks.

“It’s the one public service that almost everyone likes and nobody dislikes,” Mr. Benepe reflected when he paused from greeting fellow parks advocates and former colleagues—a task he balanced adroitly with grabbing hors d’oeuvres and sipping wine. “Arresting someone is not fun, and neither is picking up garbage or cleaning the sewers,” he continued. “These are services that deal with the miseries of life, and someone has to do them—they’re important jobs. But the parks department deals with the happy aspects of life.”

Mr. Benepe is clearly a practiced hand at events like these, unburdened by the contradictory demands of schmoozing and snacking that befuddle many a cocktail circuit newbie. By his count, he was on 76 different boards at one point.

“Adrian was always a great fund-raiser,” said Tupper Thomas, the now-retired head of the Prospect Park Alliance. “Every party I went to, he was there, and he had always been to two or three parties before that.”

That Mr. Benepe devoted so many evenings to such events was not merely in the service of some ancillary duty, but the machinery by which the department augments its $300 million to $400 million yearly city operating budget with some $160 million in private funding—a controversial model in which parks creation and salvation increasingly falls under the purview of private donors, and the strings that they may or may not chose to attach to their generosity.

But it is also largely responsible for the parks system’s restoration and expansion; during Mr. Benepe’s decade-long reign, the city added 730 acres to the system with 2,000 more in the works at Fresh Kills, the biggest expansion since Robert Moses, including blockbusters like the High Line, Governor’s Island and Brooklyn Bridge Park (all partially financed with private dollars). While the department benefited greatly from Mayor Bloomberg’s favor ($4 billion was budgeted to create new parks during his three terms), the city’s parks renaissance is, in many ways, a story of cocktail parties, concessions, condos and an ever-growing number of money-wrangling nonprofits like the Restoration Fund, at whose soirée a meal of beef and scalloped potatoes was followed by an “auction” where attendees made multi-thousand dollar donations to congratulatory applause, capped by a Bette Midler-led sing-a-long.

The challenge that Mr. Benepe faces in his new role is how to help other cities like Chicago and Newark replicate New York’s parks successes. The difficulty in doing so, however, hinges on how much of what happened in New York during the last 10 years was the culmination of a unique set of factors: a wealthy populace, a huge network of advocates, the support and favor of a powerful mayor, and a city willing accept private-sector partnerships, for better and worse. Which raises the question of whether the circumstances that gave rise to our current system will continue in a post-Bloomberg era, and perhaps more importantly, whether New Yorkers will want them to.

Concrete Plant Park in the Bronx when it was an industrial wasteland (photo courtesy NYC Parks).

If Mr. Benepe’s first job was predictably unpromising, it was also unusually prescient of his future profession. At 16, he took a summer job with the parks department and was assigned to mopping duty at a swimming pool, which morphed into picking up trash at a park on East 10th Street. It was 1973, the parks system was at its nadir, and no one could be bothered to do much about it.

“There was a purposeful avoidance of work,” Mr. Benepe said. “When I got there, my supervisor said, ‘You know, kid, let me tell how things work here. You’re supposed to come in at 8, you can come in at 9. You’re supposed to take half an hour for lunch, you can take an hour or an hour and a half. You’re supposed to leave at 5, you can leave at 3:30.’ Anyway, he went back to sleep in the office and said, ‘Warn me if the foreman is coming.’ It was the most unlikely scenario to say you’re going to make your career in this department.”

The park after its transformation (Malcolm Pinckney/NYC Parks ).

Nor did he intend to. Mr. Benepe went to Middlebury College, where he met his wife, and after graduation he took an unpaid internship at a small newspaper; he sustained himself financially by working at the information desk in the Port Authority. One day, his editor sent him out to scare up a story about the changes being implemented by new Central Park administrator Betsy Barlow Rogers. Mr. Benepe was so impressed that, after he wrote the story, he left to become one of her early park rangers.

In Central Park, Mr. Benepe’s job fell somewhere between guide and security guard. “Belvedere Castle was abandoned and covered in graffiti, homeless people were living inside it, and many of the walls around the castle had been pushed into the park below. Burned-out buildings littered the landscape; there were drug dealers. Even Miss Piggy got mugged in Central Park,” Mr. Benepe recalled, referring to a scene in The Muppets Take Manhattan. “They had let the parks decay so tremendously that they became scary instead of being something nice for the city.”

After some time on the job, he gave up on parks because of “too much bureaucracy,” and went to journalism school. After graduation, he worked at a New Jersey newspaper for about six months before the head of the park rangers asked if he wanted to come back, for a significantly higher salary.

But it wasn’t only the money. “I had done some things as a park ranger that appealed to me,” Mr. Benepe recalled. “I had found lost kids and done first aid on people who were badly hurt and arrested bad guys, even though I didn’t have powers of arrest—I probably did that half a dozen times. I just got, and continue to get, a great deal of psychic reward from public service.”

He first came to the attention of former parks commissioner Henry Stern in the early 1980s via the responses he wrote to public letters. “Adrian wrote the best letters—he was Bright Eyes in Planet of the Apes,” said Mr. Stern. “They were clear and responsive, typed and well-spelled.”

In the last few decades, the parks department has worked closely with alliances like the Central Park Conservancy.

Among Mr. Benepe’s first tasks when he became parks commissioner in early 2002 was rebuilding the ash-damaged parks of Lower Manhattan in the aftermath of 9/11. The other was setting in motion the process to bring Christo’s Gates to Central Park—a plan that had been in the making for decades but which seemed unlikely to come to fruition until the Bloomberg administration flagged it as a priority.

In Mr. Benepe’s view both these things were in service to the same goal: rebuilding the civic spirit and demonstrating that the city was not only viable, but the thriving tourist destination that it had once been. Though by the time the Gates was actually mounted in February 2005, this seemed a foregone conclusion, and today, such worries are only a distant memory, with Central Park’s 25 million visitors a year making it the world’s most visited city park.

That parks could make an argument on behalf of a city may seem improbable, but parks play an integral role in New Yorkers’ lives even if their uses are resolutely prosaic; few of us have access to any greenspace but a public one. Mr. Benepe still remembers meeting a man in the ramble when he was a park ranger who told him that “the city had really lost something, it really started going down the tubes when we gave up the parks and let the hoodlums take over and the only way we’re going to make this city great again is when we have great parks,” Mr. Benepe recalled. “Boy, was that prescient and wise. It was 34 years ago and it really stuck with me.”

Mr. Benepe is not the first parks commissioner to lean on the generosity of the city’s elite—the Central Park Conservancy was started in 1980, and the advocates, alliances and friends of groups that cultivate wealthy denizens as donors have been growing in number ever since—but he and Mr. Bloomberg have ushered in an era in which the impact of those partnerships is greatly heightened. (“Without telling us to do public private partnerships, the administration encouraged us to be creative,” Mr. Benepe said.)

Given that the city’s parks were conceived as democratic spaces, opening them up to private interests and uses can feel like a violation. This is particularly true when those private uses restrict or limit public enjoyment, as with Columbus Circle’s Damrosch Park, where events like Fashion Week and the Big Apple Circus close the space to the public for up to 10 months a year (a lawsuit is pending).

And in a city where access to many things is restricted by money, and the poor and middle-class increasingly feel that they are being pushed out, the extension of that ethos to the city’s parks—one of the places where people can forget the grinding imperative to make and spend that defines so many aspects of life here—seems like an added cruelty.

And yet.

An urban park is not one of those sylvan gifts bestowed by the heavens. Its creation and upkeep require money, and lots of it. And the expansion of the parks system—a universally popular move, even if its funding is not—was directly tied to the Bloombergian real estate development that many view as the worst culprit in the gilding of New York. It was, after all, the Bloomberg rezonings that created both Williamsburg’s despised condos and the necklace of parks threaded between them and the water.

Neither Brooklyn Bridge Park nor Hudson River Park could have existed were it not for private partnerships; the condition of their creation out of defunct piers and wharves was that they pay for their own massive upkeep. Brooklyn Bridge Park has managed to do so by building lucrative condos, but Hudson River Park has struggled mightily, prevented in its charter from building residential developments to generate income.

Mr. Benepe, who spent the entirety of his career watching private funding do what public budgets could not, grows frustrated when the wisdom of building condos in Brooklyn Bridge Park is questioned.

“It wasn’t a park before!” he cried. “It was spelled out in the agreement, signed prior to Bloomberg, that a portion at the edge of the site was going to be set aside for commercial purpose, whose revenue would go to maintain the park. That was the deal to build the park.”

Still, few would wish the parks unmade, and fewer still can offer viable alternatives beyond the seemingly impossible: fund them entirely with tax revenue. It is telling that mayoral candidate Bill de Blasio’s plan to avoid building a Major League Soccer stadium in the chronically-neglected Flushing Meadows park was to enhance the park’s private revenue streams.

Nonetheless, Flushing Meadows has proved queasy-making for even the biggest public-private advocates. The need to sacrifice yet another chunk of the park suggests a future in which the city backs away from its financial commitment to the parks, putting city treasures in hock to pay for basic services. It also emphasizes the fact that while organizations like the Central Park Conservancy may allow the parks department to funnel funds to poorer parks, some parks are undeniably better maintained than others.

Whether that’s a problem is debatable. If it is, no has presented any workable solutions, least of all forced redistribution. The Conservancy manages to draw donations like John Paulson’s whopping $100 million check precisely because the incredibly wealthy people who live clustered around Central Park want to give to Central Park, not Flushing Meadows. Mr. Benepe readily admits that the success of the Central Park Conservancy is a unique, an accident of wealth and density that even Prospect Park cannot replicate.

Mr. Stern opined that half of the parks commissioner position was “fighting against people who want to steal the parkland,” recalling the battle he fought against a wealthy donor who wanted to build an aviary in the middle of Bryant Park and a “grotesque” plan to put a race track in Flushing Meadows.

“I found that Adrian always did what he could to defend the parks and get new parks,” he said.

“When you have to say ‘no,’ the discussions can get incredibly heated,” he said. “You learn to apologize when you know you’re right and say, ‘I’m sorry. What can I do to make it better?’

As for his relationship with Bloomberg, he said that they seldom disagreed. “There are projects which I won’t name that I didn’t fully agree with, but overall, I thought the mayor was so good for parks that I was willing to stifle my own beliefs because the overall picture was so good,” Mr. Benepe elaborated.

“There have been many great transformations in the last decade,” he continued, “but the thing that you see is the public spaces, and you see these vast new parks along the Hudson River and Brooklyn Bridge Park, Dumbo and the Bronx River and all these little greenstreets and plazas and the million trees. The mayor has done a lot of great work, but the physical legacy, the one that you see, is the parks.”

When we visited Mr. Benepe at the Trust for Public Land’s hushed Noho office on a recent afternoon, the hustling madness of Broadway below felt very far away.

Even at 56, he retains a boyish air, perhaps owing to his penchant for bicycling and backpacks and the somewhat impish expression that he often wears on his face, one that registers somewhere between a smirk and a smile (a look that was described as “smug” by Staten Island Councilman James Oddo when the two clashed over flooding during Hurricane Irene).

Several of Mr. Benepe’s friends and former colleagues said that they were surprised that he decided to leave a job he clearly loved more than a year before the end of Mr. Bloomberg’s last term. Few positions provide as many opportunities for having a direct impact as being a city commissioner.

But commissioners rarely outlast their mayors. Mr. Benepe said that he didn’t want to pass up an opportunity to continue working in the world of urban parks.

“Even if I had stayed it out and been rehired by the next mayor, there’s always the fear of overstaying your welcome,” he said, shrugging. “People just get tired of public officials if they’re there too long.”

Elmhurst Park, post renovation (Daniel Avila/ NYC Parks).

Taking another job, especially one where he could build on so much of the work he’d done commissioner, was the practical thing to do. And if nothing else, Mr. Benepe’s time in the parks department has made him a resolutely practical person. After all, the city’s parks were revitalized by those who found ways to move forward without adequate city funding, funding that they surmised would never be forthcoming. As for the murkier moral questions raised by such solutions, they were subsumed by the details of planting trees and rebuilding playgrounds, renovating parks and opening swimming pools.

The phone rang. It was Giants co-owner Jonathan Tisch returning his call; Mr. Benepe had been trying to get the Super Bowl involved in a legacy parks project in New Jersey, where the event is going to be held in 2014.

The men chatted briefly. “Well, I’ve been traveling a lot, trying to help other cities do what New York has done,” Mr. Benepe said. “The really interesting thing I learned is how efficient New York is. Other places, they have weak mayor systems, or you know, the mayor doesn’t control things and there are these big battles.” He laughed a little ruefully. “People say New York isn’t efficient, but you’d be surprised.”

I guess the writer does not get a round much, or else she would know that much of the park system remains overgrown and shabby, particularly where rich benefactors are not dumping money into their local preserves. I suggest that she pay a visit to the outer boroughs and see what overgrown and shabby looks like.